A packet of cigarettes normally comprises an inner package defined by a group of cigarettes wrapped in a sheet of packing material (normally foil with no glue); and an outer package, which encloses the inner package, is stabilized using glue, may be cup-shaped and defined by a sheet of outer packing material folded about the inner package (soft packet of cigarettes), or may be defined by a rigid, hinged-lid box formed by folding a rigid blank about the inner package (rigid packet of cigarettes).
To fold a sheet of packing material about a group of cigarettes, a packing unit is known comprising two or more packing wheels, which have respective peripheral pockets for receiving and housing the group of cigarettes as the sheet of packing material is being folded. Normally, at a feed station, a group of cigarettes is inserted into a pocket on a first packing wheel together with a sheet of packing material, which folds into a U about the group of cigarettes; and the two flaps of the U-folded sheet of packing material projecting from the pocket are then folded one on top of the other and onto the group of cigarettes to form a tubular sheet of packing material. At a transfer station between the first packing wheel and a second packing wheel, the group of cigarettes enclosed in the tubular sheet of packing material is transferred from a pocket on the first packing wheel to a pocket on the second packing wheel; and folding devices fitted to the second packing wheel then perform further folding operations on the tubular sheet of packing material.
The group of cigarettes enclosed in the tubular sheet of packing material is transferred using a pusher which engages a first base wall of the group of cigarettes, and a counter-pusher which engages a second base wall, opposite the first base wall, of the group of cigarettes. In other words, the pusher and the counter-pusher grip the group of cigarettes between them as it is being transferred, to hold the group firmly together (i.e. to prevent undesired transverse movements of the cigarettes in the group, that may alter the shape of the group). Despite the gripping action of the pusher and counter-pusher, however, a far from negligible percentage of the groups of cigarettes have been found to undergo deformation as they are transferred between the two packing wheels, thus inevitably resulting in rejection of the groups.